Catalyst for olefin polymerization

ABSTRACT

A catalyst for olefin polymerization which comprises:   (A) a catalyst component obtained by reacting (a) pentadiene or a derivative thereof with (b) an alkali metal and subsequently reacting the reaction product with (c) a titanium compound or zirconium compound, and   (B) aluminoxane. t

This is a division, of application Ser. No. 255,085, filed 10/7/88 Pat.4,871,704.

BACKGROUND OF THE INVENTION

Field of Industrial Application

The present invention relates to a catalyst for olefin polymerization.

Since the synthesis of cis-1,3-pentadiene anion in 1979, complexes ofthis compound with a transition metal have been known. However, noinstances have been reported in which its transition metal complex isemployed as a catalyst component for olefin polymerization.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a catalyst forolefin polymerization which is based on a pentadiene anion complex.

The present inventors found that a catalyst formed by the combination ofan (open) pentadiene complex of zirconium and aluminoxane has an abilityto polymerize olefins. This finding led to the present invention.

The gist of the present invention therefore resides in a catalyst forolefin polymerization which comprises: (A) a catalyst component obtainedby reacting (a) pentadiene or a derivative thereof with (b) an alkalimetal and subsequently reacting the reaction product with (c) a Group 4b(Periodic Table-Handbook of Chemistry and Physics, 49th Edition, TheChemical Rubber Co., Cleveland, Ohio) metal compound, preferably atitanium compound or zirconium compound, and (B) an aluminoxane.

DETAILED DESCRIPTION OF THE INVENTION

1. Raw materials for catalyst component

(a) Pentadiene or a derivative thereof

The pentadiene or a derivative thereof (referred to as component (a)hereinafter) is represented by the formula below. ##STR1## (where R¹denotes a hydrogen atom, hydrocarbyl group having 1 to 8 carbon atoms,or --Si(OR⁴)₃ group; R² and R³ which can be the same or different eachdenote a hydrogen atom or a hydrocarbyl group having 1 to 8 carbonatoms; R⁴ denotes a hydrocarbyl group having 1 to 5 carbon atoms.)

Examples of component (a) represented by the formula above include1,3-pentadiene, 1,4-pentadiene, 3-methyl-1,3-pentadiene,3-methyl-1,4-pentadiene, 2,4-dimethyl-1,3-pentadiene,2,4-dimethyl-1,4-pentadiene, 3-ethyl-1,3-pentadiene,1,5-bistrimethoxysilyl-1,3-pentadiene, and1,5-bistrimethoxysilyl-1,4-pentadiene. Particularly preferable amongthem is 1,3-pentadiene.

(b) Alkali metal

The alkali metal (referred to as component (b) hereinafter) includeslithium, sodium, potassium, rubidium, and cesium. Potassium is mostdesirable among them.

(c) Titanium compound or zirconium compound

The titanium compound or zirconium compound (referred to as component(c) hereinafter) includes titanium tetrahalide or zirconium tetrahaliderepresented by the formulas below.

TiCl₄, TiBr₄, TiI₄, ZrCl₄, ZrBr₄, and ZrI₄.

TiCl₄ and ZrCl₄ are particularly preferable among them.

2. Preparation of Catalyst Component

The catalyst component pertaining to the present invention is obtainedby reacting component (a) with component (b), and then reacting thereaction product with component (c).

(A) Reaction of component (a) with component (b)

The reaction of component (a) with component (b) is usually accomplishedin a solvent such as tetrahydrofuran, diethyl ether, and dioxane. Themolar ratio of component (a) to component (b) is 1 to 10. The solventshould preferably contain an amine such as trimethylamine,triethylamine, tributylamine, trimethanolamine, triethanolamine, andtriisopropanolamine.

The reaction is usually carried out at -50° C. to +100° C. for 0.5 to 20hours.

The above-mentioned reaction gives pentadienyl anion. Its cis/transratio can be controlled by changing component (b) and solvent to beused. In the case were component (b) is potassium and the solvent istetrahydrofuran, the cis content can be 98% or above. The ligand whichis formed in this reaction presumably has a structure of ##STR2## (openpentadiene complex).

(B) Reaction with component (c)

The reaction product obtained in step (1) above is subsequently reactedwith component (c). This reaction is usually carried out in a solventwhich may be used in step (A) above. The reaction is performed at -100°C. to +50° C. for 5 to 50 hours. The reaction temperature may begradually raised as the reaction proceeds.

The amount of component (c) should be 0.1 to 2 mol for 1 mol ofcomponent (a) in the reaction product.

The catalyst component pertaining to the present invention can beprepared as mentioned above. The catalyst component may be brought intocontact with a metal oxide.

The metal oxide that can be used for this purpose is an oxide of anelement selected from Groups II to IV of the periodic table. Examples ofthe metal oxide include B₂ O₃, MgO, Al₂ O₃, SiO₂, CaO, TiO₂, ZnO, ZrO₂,SnO₂, BaO, and ThO₂. Preferable among them are B₂ O₃, MgO, Al₂ O₃, SiO₂,TiO₂, and ZrO₂. Particularly desirable are Al₂ O₃ and SiO₂. These metaloxides can also be used in the form of compound oxide such as SiO₂--MgO, SiO₂ --Al₂ O₃, SiO₂ --TiO₂, SiO₂ --V₂ O₅, SiO₂ --Cr₂ O₃, and SiO₂--TiO₂ --MgO.

The above-mentioned metal oxides and compound oxides should preferablybe in the form of anhydride in principle; but they may contain a traceamount of hydroxide which is present under normal conditions.

The metal oxide should be calcined at as high a temperature as possibleprior to use in order to remove poisonous substances, and, aftercalcination, it should be kept away from air.

The contacting of said catalyst component with a metal oxide is usuallyachieved in an inert hydrocarbon such as hexane, heptane, cyclohexane,benzene, toluene, and xylene at a temperature in the range of roomtemperature to the boiling point of the hydrocarbon for 0.5 to 20 hours.The amount of the metal oxide is 1 to 500 parts by weight for 1 part byweight of said catalyst component.

Cocatalyst Aluminoxane

Aluminoxane is a compound represented by the formula below. ##STR3##(where R⁵ denotes a hydrocarbyl group having 1 to 8 carbon atoms and nis a positive integer of from 4 to about 26 and preferably 14-20.) It isusually produced by reacting an organoaluminum compound of the formulaAlR₃ ⁵ with water.

Examples of the organoaluminum compound include trimethyl aluminum,triethyl aluminum, triisobutyl aluminum, trihexyl aluminum, trioctylaluminum, and triphenyl aluminum. Trimethyl aluminum is particularlypreferable.

The organoaluminum compound can be reacted with not only ordinary waterbut also water of crystallization in iron sulfate or copper sulfate.

The catalyst of the present invention is composed of the catalystcomponent and aluminoxane prepared as mentioned above. The ratio of thetwo components is such that the amount of aluminoxane is 1 to 10⁶gram-atom (in terms of aluminum) for 1 gram-atom of titanium orzirconium in the catalyst component.

Polymerization of Olefins

The catalyst of the present invention can be used for thehomopolymerization of α-olefin such as ethylene, propylene, 1-butene,1-hexene, 4-methyl-1-pentene, and 1-octene and also for thecopolymerization of said α-olefin with other olefins.

The polymerization reaction may be accomplished in either gas phase orliquid phase. The liquid phase polymerization may be accomplished in aninert hydrocarbon such as n-butane, isobutane, n-pentane, isopentane,hexane, heptane, octane, cyclohexane, benzene, toluene, and xylene, orin a liquid monomer. The polymerization temperature is usually in therange of -80° C. to +150° C., preferably 40° to 120° C. Thepolymerization pressure is, for example, 1 to 60 atm. The molecularweight of the polymer can be properly regulated by the aid of hydrogenor any other known molecular weight modifier added to the polymerizationsystem. In the copolymerization, a major olefin is copolymerized withother minor olefin in an amount up to 30 wt%, preferably from 0.3 to 15wt%, of the major olefin. The catalyst of the present invention is usedfor polymerization reaction which is carried out continuously orbatchwise under normal conditions. The copolymerization may be carriedout in a single step or in two or more steps.

Effect of the Invention

The catalyst of the present invention is based on a pentadiene anioncomplex, and it enables the polymerization of olefins.

EXAMPLE 1 Preparation of catalyst component

In a reaction vessel, with the atmosphere therein replaced with nitrogengas, was placed a mixture of 16.5 ml of tetrahydrofuran (THF) and 8.5 mlof triethylamine and then 1.57 g of metallic potassium. To the reactantswas added dropwise 9 ml of 1,3-pentadiene at 0° C. The reactants wereheated up to room temperature over 2 hours. To the reactants was addedadditional 10 ml of THF. The reactants were heated to 40° C. until thereaction was completed. The reaction solution was cooled to 0° C. tocause orange crystals to separate out. The crystals were filtered offand dried. The yield was 67 mol%. The reaction formula is as follows:##EQU1##

The thus obtained crystals were dissolved in THF, and the solution wasadded dropwise at -70° C. to a THF slurry containing 1.86 g of ZrCl₄.The resulting slurry was slowly heated to room temperature over 24hours. Solids were filtered off and the filtrate was freed of THF bydistillation to cause solids to separate out. The solids which hadseparated out were dissolved in toluene containing 5 wt% of THF.Insoluble matters were filtered off and the filtrate was freed ofsolvent by distillation. Upon drying the precipitates, there wasobtained 0.4 g of dark brown crystals (catalyst component).

Polymerization of Ethylene

In a 1-liter glass autoclave, with the atmosphere therein replaced withnitrogen gas, were placed 50 mg of the catalyst component obtained asmentioned above, aluminoxane (10 miligram-atom as aluminum), and 250 mlof toluene. (The aluminoxane is one which was synthesized from trimethylaluminum and CuSO₄.5H₂ O.) Into the autoclave was introduced ethylenegas. The polymerization of ethylene was performed at 50° C. for 1 hour.The catalytic activity was 143 g/g-Zr.atm.hour. The resultingpolyethylene was found to have a viscosity-average molecular weight of1.5×10⁶.

EXAMPLE 2

A toluene solution containing 0.15 g of the catalyst component preparedin Example 1 was added to a toluene slurry containing 3 g of aluminawhich had previously been calcined at 500° C. for 6 hours. The reactionwas performed at 70° C. for 2 hours. The resulting solids werethoroughly washed with toluene and n-hexane and dried. The dried solidswere found to contain 5.6 mg of zirconium per gram.

The polymerization of ethylene was performed in the same manner as inExample 1, except that the catalyst component was replaced by the solidsobtained in the above-mentioned step. The catalytic activity was 290g/g.Zr.atm.hour.

We claim:
 1. A process for the polymerization of one or more olefinshaving from 2 to 8 carbon atoms which comprises contacting the olefin(s)in a polymerization reactor under polymerization conditions in thepresence of a catalyst comprising:(i) a catalyst component obtained byreacting,(a) a pentadiene represented by the formula: ##STR4## whereinR¹ represents hydrogen, a hydrocarbyl group having from 1 to 8 carbonatoms, or a --Si(OR⁴)₃ group, R² and R³, which can be the same ordifferent, each represents a hydrogen or hydrocarbyl group having one 1to 8 carbon atoms and R⁴ represents a hydrocarbyl group having 1 to 5carbon atoms with (b) an alkali metal, and contacting the producttherefrom with, (c) a Group 4b metal compound, and (ii) an alumoxane. 2.The process in accordance with claim 1 wherein the Group 4b metal isselected from zirconium and titanium.
 3. The process in accordance withclaim 1 wherein the Group 4b metal compound is a titanium halide or azirconium halide.
 4. The process in accordance with claim 2 wherein theGroup 4b metal is a titanium halide or a zirconium halide.
 5. Theprocess in accordance with claim 1 further characterizing beingsupported on a metal oxide.
 6. The process in accordance with claim 4wherein the catalyst component is supported on a metal oxide.